| 摘要 |
A video driver in a computer system is used to map a large video frame buffer into the logical address space above physical memory while the computer system is operating in WINDOWS STANDARD mode. The requirements of the necessary address space for the frame buffer (i.e., the size of the frame buffer), and the size of physical memory are determined. If there is sufficient address space above physical memory in which to map the frame buffer, the video driver attempts to map the frame buffer there in that address space. The desired physical and linear addresses for the frame buffer are determined. If the video driver detects that MICROSOFT WINDOWS is operating in standard mode, it searches memory to find the page directory that MICROSOFT WINDOWS created. Once the page directory is found, the driver creates a new page table to map the frame buffer into the desired linear address range and adds a new entry to the existing page directory to point to the new page table.
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